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Re: Is a rebreather for me

I will give Lyle a call anyway, it can't hurt to ask and read between the lines. if they did mod level 3 with you maybe they are diving deep collecting rare fish. This wouldn't be as hard work in one sense because you only need to catch one or two per dive. I am too old to be thinking about going in to the death zones. I only work shallow. I am thinking of a return hose away from my hookah regulator to gas off bubbles 10-20 metres behind me. I am still working out if it can be done without it causing my regulator to constantly free flow?

Re: Is a rebreather for me

Originally Posted by chaetodon

Thank you for the tips, this is increasing my knowledge. There is a lot to learn and experience goes a very long way. I had some thoughts previous that the solenoid would make sounds when it kicks in. Your post has confirmed that to me. It is the experience of these little things that all add up to knowing the ins and outs of your gear. One guy mentioned to me today how the dynamic is different to OC or SSBA. When I have been taking a breath or exhaling on OC, I have been so used to unconsciously altering my buoyancy that the RB is going to feel very strange until I am used to it. I did know this superficially but now its hit home how different this will be. I haven’t even been near a CCR yet! You asked me about work load and yes sometimes I am in current but what really gets me panting is sometimes I need to do a quick sprint to catch a fish. Most of the time its relaxed and stalking but if one behaves tricky or bolts away I need to exert for a short while to catch it. This may be a dozen deep breaths before I can relax once again. Something to consider, or maybe for tricky fish I have to let it go if using CCR. What’s the amount of breath cycles if I am in a relaxed state before the system needs to dump? Also what is the scenario under a heavy workload? I guess this varies greatly on the depth I am at but I am interested to know how much rate the diluent and the O2 is used up. I have a great deal yet to understand about the transition of the gases. I wish I could spend a day going through this with you, I think I could pick up a great deal. The big problem I have here is doing a courses is $3000 and I will be treated like a freshman. I need to do 100 hours advanced nitrox before they will allow me to go near CCR. To fill you in I am an ADAS approved diver, It is a commercial qualification here, the work place health and safety part of the government made us do it after years of diving without the need for qualifications. After this we have been diving so long professionally we just took upon and started using O2 years ago without getting certification etc. With all due respect to recreational and tech divers It’s a different world for a pro diver. I will get flamed for saying this but a certificate means nothing to me personally, a piece of paper is not going to keep me alive down there. I understand all this from the teacher’s aspect, it is to do with liability issues and also they need to earn their living, plus it’s so expensive because of the stigma surrounding CCR’s. I naively didn’t want anything to do with RB for my whole life because I thought they kill. New people learning, I agree should do the right thing and get their certification but I am 60 and have been doing this forever and will be treated as a novice if I sign up for a course. It’s a dilemma for me but I will see what I can learn and then weigh it up from there.

I looked up Prisms and there doesn’t seem to be too many over here for sale. There are megs, optima 2, Poseidon VI, and inspiration classic which a couple of guys suggest to try out first because they are cheap. (Bazza from Southern Cross recommends APD Evolution Plus, or JJ-CCR. These are probably newer expensive models) What’s your opinion, are any of these similar to the Prism 1 you mention? I like your comments of considering more toward MCCR or basic ECCR than too much integrated sub system technology. But considering my workload, I guess you mean I would need something simple that’s still quickly responsive if my activity is sporadic?
Are there any other units you recommend I look at? So many different brands???

P.S. I also came across a Queensland Grouper on OC or Hookah, I forget. He was behind the stern of a large sunken barge we dive on. He was curious to some extent and we were facing each other about 20-30 feet away. I slowly edged closer until I got about 12-15 feet away. He spooked and turned on a dime, flicked his tail and shot off at unbelievable speed 30 knots or whatever. The shockwave hit my chest and head like a powerhead going off. Wow from that distance! Now I can appreciate what happened to you being next to the big fish when he did that. It must have felt like a submarine depth charge going off or what?? Ha ha.

Yes, the solenoid makes a quiet click when it fires. However, it is right behind your head and I have never seen wildlife react to it.

Yes your buoyancy will be very different, as it changes with depth until you either add dil to compensate for descent, or vent gas on ascent. However, you are able to point yourself in whatever direction you want to go and just kick, that's the upside, a certain increase in maneuverability.

My high exertion scenarios resulted from strong down or up currents on exploratory dives. Also, sometimes during a live drop in a strong current where you have to get down to depth rapidly in order not to miss the dive site, like a pinnacle or a wreck.

3000 Australian dollars sounds very high for a course, and as far as I know PADI and TDI only require basic nitrox for air dil recreational depth mod 1.

One of the many great things about CCR is the fact that your gas consumption does not vary with depth, aside from the initial volume of dil necessary to attain proper loop volume at depth. As for duration, 3 L cylinders of back gas on the rebreather would theoretically provide you with near to 10 hours of gas. The limiting factor is the scrubber duration.

I'm not sure what you mean about dumping? CCR's only vent/dump gas on ascent. It is SCRs that vent regularly.

The electronics of the Prism 1 are not like any other commercially available CCR's. There is no other ECCR which is as simple, and it is virtually immune to pressure related electronics or battery failures. The Prism is so simple that it can be dived with a complete electronics failure as the secondary PO2 meter is driven directly by the voltage from the sensors.

As for other rebreather's, all of the ones you mentioned are more complicated than the Prism and thus don't appeal to me. I have seen too many false alarms from the more complicated units that either prevented dives or forced them to end prematurely. I am a KISS principle guy not just for ease of maintenance and troubleshooting, but perhaps more importantly because the simpler the unit, the more involved the diver is in the operation of it, and hence more aware of all its functions and more likely to know when something is wrong at an early stage.

And yes, I will never forget my encounter with that grouper. I'll never forget the concussion of the tail slap and that I almost lost my mask in the turbulence that followed. Nor can I forget the enormous size of its eyes, or the tremendous speed it attained, like an obese, stubby rocket as it vanished out of sight in less than second..

Re: Is a rebreather for me

Prism 2 is available here but is big dollars. I can't see any prism 1 for sale anywhere. Other guys have suggested AP classic just to get a feel. I understand your concept silent running, more confidence less to go wrong and know your gear. By dumping it was a problem I thought I was going to have when reading the AP manual. look a couple of posts back and my sawtooth profile in the water column. Thanks

Re: Is a rebreather for me

Originally Posted by chaetodon

Hmmm. Reading the AP classic manual and early on I see the first stumbling block for me is these rb's like lateral travel. Common sense physics of buoyancy I suppose, but I use the water column a great deal stalking fish and rising quickly to hover up to 10 feet above them (sometimes 15-20 feet) then scooting down to net them, inhale to rise and exhale to drop. There is a bit of table tennis and mexican standoff action when I stalk and finally spook one in to the net. The big problem for me I see is I need both hands free when I am doing this action. This is going to require developing some refined technique if I have to exhale out of the loop and add diluent at the same time I swoop down. I am probably doing this stalking action more so not to scare the fish from my bubbles on SSBA or OC. Over the years I am not conscious to why I am doing this but it works. A lot of rethinking to do and the only way to know is practice and try it. Like Bazza said it will be like being a novice all over again. I am only early in to the book but I see these mobility issues will be my biggest challenge. I just need to evolve two more sets of hands. Unless I can add diluent with a hand trigger or maybe by having more breaths in the bag initially. I cant see any problems so far with reading PPO2 and setpoints, maintaining gear etc. Just a headache if water is getting in. Any suggestions anyone ??

I am not concerned about wasting diluent or O2, I have it by the bucketful as long as I don't empty it in one long dive.

ello sir
you can do the up and down thing hands free ,
only problem is if you did said up and down 10 times on a dive you would prob use half your 3l dill .

also comming up fast ambient pressure is working against you ie po2 is droping and gas expanding
and if you were ot over shoot and not able to stop your self , o2 could get to low . ap unit is good at keeping set point but that also works against you . ie it will piss in more gas and you get more lift , (see hot mix to adv below ) hot mix good for scr bail out also ,

its Not something us none fish guys do , your going to need some play time ,
and a hud for sure ,

ps
your prob better of using a nitrox dill rather than air , (If your after hands free) just a suck and blow dive lol

id think your starting point for set up
will be on board o2 and nitrox feed adv with the nitrox , o2 feeds solenoid (hot mix to adv will stop the solenoid from chasing its tail ) when in peter pan mode .lol

offboard o2 and offboard air or a weak nitrox on the buttons ie manual flight , and use for bail out, so regs on, also air/weak nitrox can be used to verify cell s at depth some thing round .25nitrox good to 30m

your never going to be peter pan with a ccr lump on your back , sorry, its never going to be like your 50l hookah set up (work on that exhaust bubble catcher )

how long are your bottom times and whats your avg and max depth , what,s the number of ups and downs also what s the max up travel

solelnoid
i was about a foot away from a large turle as it feed , when my solelnoid kicked in it stopped feeding and looked at me so it did hear it put it was not spooked ,

Re: Is a rebreather for me

Originally Posted by chaetodon

rising quickly to hover up to 10 feet above them (sometimes 15-20 feet) then scooting down to net them, inhale to rise and exhale to drop.

That isn't a good use for a re-breather. As well as wasting diluent, you will increase task loading and generate lots of bubbles when venting gas from the loop. Ascending too quickly can easily get into a runaway ascent.

My usual practice on any dive involving a lot of up-down zig-zag is to forget maintaining a steady high set point and keep the rebreather electronics at low set point, pushing that up towards the high set point manually. But where possible its always better to avoid a lot of up-down, and certainly not fast up-down.

Re: Is a rebreather for me

Originally Posted by chaetodon

Prism 2 is available here but is big dollars. I can't see any prism 1 for sale anywhere. Other guys have suggested AP classic just to get a feel. I understand your concept silent running, more confidence less to go wrong and know your gear. By dumping it was a problem I thought I was going to have when reading the AP manual. look a couple of posts back and my sawtooth profile in the water column. Thanks

A Prism 1 is a rebreather equivalent of a '60s VW van. Fun to drive but a pain to keep running.

Re: Is a rebreather for me

Originally Posted by wedivebc

A Prism 1 is a rebreather equivalent of a '60s VW van. Fun to drive but a pain to keep running.

Very funny! But honestly, I've never thought it was such a pain, a few quirks, but nothing requiring daily troubleshooting. 700+ hrs with no dives missed because of a false scrubber alarm, failure to calibrate, cracked handset or deco computer lockout..